Machine for plating surgical needles



June 21, 1960 R. c. BELL 2,941,501

MACHINE FOR PLATING SURGICAL NEEDLES Filed June 10. 1958 INVENTOR.

ROBE/FT CHARL E5 BE LL BY M M W ll A 7'7'0R/VEY United States Patent can Cyanamid Company, New York, N.Y., a corporation of Maine Filed June 10, 1958, Ser. No. 741,180

1 Claim. (Cl. 118-418) This invention relates to improvements in an apparatus for nickel-nickel phosphide plating needles for surgical sutures.

This application is a continuation-in-part of a joint application Serial No. 574,160, March 27, 1956, entitled Plating Surgical Needles, Reginald Marsh Banks and Robert Charles Bell, now United States Patent No. 2,865,375 dated December 23, 1958.

At present surgical needles are produced from a fairly high carbon steel so as to give a tough sharp needle point for use in suture work. Many of the needles are of the eyeless type in which various means are used for connecting a single strand of a suture to a needle. Such needled sutures are then stored until time for use. Certain sutures, such as gut sutures, must be stored in a conditioning fluid such that the suture is in proper condition for use when removed from the storing container. Needled silk sutures, and other types of sutures may be stored dry. Under either condition it is necessary that the needles remain bright and shiny and appear free from contaminaiton for esthetic reasons, as well as practical utility. In many instances the point of the needle is of a much harder metal than the shank or butt end of the needle.

In the past it has frequently been customary to store the needled gut sutures in a conditioning fluid to which a rust inhibitor had been added. The use of such a rust inhibitor induces additional problems as it may deleteriously aifect the gut or the label which is present to identify the needled suture. Among other materials sodium nitrite has been used, which is apt to discolor paper.

Obviously, it would be advantageous if a needle were available which did not require special handling to prevent corrosion. The requirements are very rigorous because the cracks and crevices present in the flange portion of the eyeless needle,which are necessary so that the needle may be securely clamped around the suture, are such that it is diflicult to clean the needle, and there are many corners in which corrosion may be initiated. It would seem obvious to use a plated needle to prevent corrosion. However, conventional plates such as nickel plate are not satisfactory because if a plate on the needle is sufliciently thick to prevent corrosion, the plate tends to become brittle, and flakes oif when the flange of the needle is closed about the suture. It would thus seem that there are conflicting requirements, which have in the past presented insuperable difliculties.

It is necessary therefore to secure a plate which is smoth, uniform and sufficiently ductile to remain on the needle during subsequent operations, which is bright and shiny in order to be acceptable, and insures corrosion-resistance. The nickel-nickel phosphide plate is superior in corrosion-resistance to electrolytic nickel plate. Surprisingly it is found that an electrodeless plate of nickelnickel phosphide is of such characteristics that a suitable plated needle is obtained. It may be that the nickel phosphide in the nickel gives sufficient ductility and resilience so that the plate will remain on the surface of the needle 'ice without rupture even during closing operations, and the superior throwing power of an electrodeless plating solution insures that the cracks and crevices inthe flange of the needle are adequately plated and that the corners and re-entrant edges are adequately plated before the plate on any portion becomes so thick as to be brittle. Additionally, the nickel-nickel phosphide plate is thin enough so that sharp points and edges of the needles remain sharp.

Electrodeless plating solutions and processes have been disclosed from time to time. One which is particularly advantageous in conjunction with the present manufacture of surgical needles is that described in a United States patent to Brenner, 2,5 32,283, Nickel Plating by Chemical Reduction. The compositions and methods there described when applied to a mass of surgical needles gives amazingly satisfactory results.

It is desirable that to insure a smooth and uniform plate over all surfaces of the needles, that the needles be agitated during the plating operations, and by using an agitating device so that the needles are tumbled. Temperature control is desirable for the best results. Continuous agitation is convenient but not necessary. The nickel-nickel phosphide coating is smoothly and uniformly adherent over the entire surface of the needles.

It is prefered that the nickel be furnished by soluble nickel salts such that not substantially in excess of four parts by weight to parts by weight of solution of nickel ion is present and the hypophosphite radicals be present not substantially in excess of three parts by weight per 100 parts by solution.' It is preferred that the solutions be hot during use and whereas the nickel of the solutions can be exhausted during the plating process, normally the amount of nickel-nickel phosphide required for the plate is so small that it is more convenient to only partly utilize the nickel present in the solution and replace the solutions, because the plating solutions will not remain stable over an extended period of time.

The needles must be clean prior to plating, and conventional cleaning processes may be used, such as either a caustic or alkaline phosphate, or a solvent degreasing, or both followed by acid dip which activates the surface of the needles.

The plating is accomplished in a tumbling flask, which is adapted to tumble the needles, while maintaining temperature control.

It is very diflicult to measure the exact thickness of the coating on the surface of the needles either directly with a micrometer, or indirectly by area and weight relationships. As nearly as can be determined by measurements, a plate which is uniform and from about 0.05 to 0.35 thousandths of an inch gives a satisfactory plate which is sufiiciently thick to be corrosion-resistant, and sufficiently thin to be ductile enough to permit closing the flange of the needle about the suture without rupture. The nickel-nickel phosphide coating contains more than one phase, and on analysis of the plate obtained by prolonged plating, had a phosphorous content of 2.17%, although this may vary with thickness and plating conditions. Some publications report a higher phosphorous content.

The accompanying drawings show:

Figure 1, a curved eyeless needle;

Figure 2, a needled suture;

Figure 3, the plating apparatus.

As shown by Figure 1 conventional eyeless needles have a flange 12 which consists of an opened portion of the needle in which there are serrations 13. The needles in this form are plated. When being attached to the suture itself, the suture is placed in the flange, adjacent to the serrations, and the flange is closed about the suture plished by drawing the needle .forceably throughaclosing die which gives both a bending and a shearing action, which tends to scrape off theplate from theflange portion of the needle. The interior portions of the flange are particularly difficult to plate smoothly and unformly and are areas in which corrosion most easily occurs. it is impractical to attempt to electroplate the flange of a needle so that the interior portions are corrosion-protected by the plate, and the external portions are not so heavily plated as to become brittle.

As shown in Figure 3 the needles are conveniently plated in a rotating container. Because surgical needles are rather small and are conveniently plated in fairly small batches, a glass flask is convenient as a plating contated by the stirring motor 26 through a gear reducer 27. As so 'journa'led the flask can easilybe placed inland removed from the hot water zhath with a minimum of effort. Opposite the neck of the flask, when in position on the rollers, is a thermometer support 28, which is a tubular bracket, having a hole at the bottom thereof for the insertion of a thermometer. A thermometer 30 is positioned .in the thermometer support by a stopper .29. -By inserting the thermometer down into the interior of the fiaskxthe"temperatureof the lplatin-gpsolution during use is :ascertained.

Obviously, the apparatus may be modified somewhat from the details shown for purposes .of convenience detainer. As shown in Figure 3 a conventional Erlenmeyer flask 14 .has agitating dents 15 formed in the side near the bottom thereof. For example a 4-liter Erlenmeyer flask may have about a dozen dents formed equally spaced around the lower periphery by heating the glass in spots and using the blunt end of a file to force the glass wall interiorly of the flask to form a dent. lnrrotating, these dents pick up the needles and cause the mass of needles to move with the flask and be tumbledrather than sliding around the interior surface of the flask. The number or shape of .the dentsis not critical.

' The. flask is supported in a hot water bath 16. The'hot water bath may be of stainless steel. It is preferably provided with a cover 17. The bath water 18 may be heated by heating means 19, which may either be an electrical heater or a steaminjector to maintain the bath at a desired temperature usually near boiling. Inside the hot water bath is a group of support rollers. A bottom support roller supports the flask axially, and consists of a non-corrosive roller 20 rotatably mounted in a support pending upon the quantity of material to be plated in one batch, and the materials which are available for construction. The apparatus as shown, using a 4-liter flask, is convenient for plating a batch of several thousand surgical needles .at one time, depending somewhat on the size of the needles being plated.- I claim:

.-An apparatus for plating surgical needles comprising: a constant temperature bath, water therein, a rotatable one-piece glass Erlenmeyer flask having needle agitating integral protuberances interiorly thereof immersed in said bath, support rollers of non-corrosive self-lubricating plasticinsaid bath, one ,set of said rollers near the neck, a power ,driven set ofsaid rollers near the bottom of the flask, both said sets being substantially parallel to the flask axis, and a bottom said roller having an axis substantia'lly at right angles to the axis of the flask, said rollers supporting the flask with the main body of the flask atlleast partially immersed in said water, with the neck of the flask extending at an angle upwardly out of bracket 21. The roller is preferably of a non-corrosive material which is self-lubricating, such as Teflon or nylon. Such plastic self-lubricating materials do not require lubrication and resist the effects of the boiling water for long periods. The neck-of the flask is supported on neck support rollers 22 which are journaled in the neck support roller bracket 23. Near the lower part of the periphery of the flask are the rotating rollers 24 which are mounted on shafts 25, which are in turn I0- the Water, power drive means for said power driven set ofrollers, and a stationary thermometer axially extending into the mouth of the flask.

References Cited in the file of this patent UNITED STATES PATENTS 245,663 Rowley et a1 Aug. 16, "1881 1,886,170 Cruserv Nov. 1, 1932 2,761,420 'Mottet Sept. 4, 1956 2,793,965 Myets et al May 28, 19.57 2,816,846 Talmey Dec. 17,1957 

